Rotary machine



April 1963 B. SCHIBBYE ETAL 3,084,851

ROTARY MACHINE Filed Feb. 29, 1960 3 Sheets-Sheet 1 IN V EN TORS.LAURITZ BENEDICTUS SCHIBBYE an dBIANS ROBERT NILSSON ATTORNEYS April.1963 1.. B. SCHIBBYE ETAL 3,084,851

ROTARY MACHINE Filed Feb. 29, 1960 5 Sheets-Sheet 2 5 4 IN V EN TOR,

LAURI'IZ BENEDICTUS SCHIIBBYE Nd HANS ROBERT NILSSON 1.21 Ye M April 9,1963 L. B. 'SCHIBBYE ETAL ROTARY MACHINE s sget's-sheet 3 Filed Feb. 29,1960 INVENTORS: LAURITZ BENEDICTUS SCHIBBYE w HANS ROBERT NILSSON an YaATTORNEYS United States The present invention relates to rotary machinesof the kind having rotor sections cooperating with each other andprovided with helical lands and grooves for effecting compression orexpansion of a working medium. It has previously been proposed in suchdevices to operate in stages in such a way, taking a compressor as anexample, that a first stage performs a first compression which isfurther followed by a second compression stage. Both these stagesnormally must be separated from each other by means of a sealing toeliminate flow losses for which reason a pipe connection or the like isnecessary between the outlet of the first stage and the inlet of thesecond stage in order to provide the passage of the working mediumthrough the successive pressure stages of the rotary machine.

According to the conventional design such a connection consists of thecombination of flanges at the outlet of the first stage and the inlet ofthe second stage as also an external line of pipe connecting bothstages.

Even if such design of the stages into one single machine constitutes animprovement in relation to the possibility otherwise conceivable torealize multi-stage compression or multi-stage expansion, respectively,between separate single stage machines connected in series, thearrangement of previous single machines has been subject to thefollowing deficiencies.

'The external connection between the pressure stages complicates thedesign of the machine. It is further to be noted that expensive work forthe assembly is added thereto.

The invention has for its aim to provide an improved arrangement bymeans of which a multi-stage machine of the kind here dealt with can bedesigned as an integral unit without requiring any external connectionsbetween the stages of the aggregate. For that reason it is proposed thatthe connection between the stages comprises a channel located in thecasingitself accordingly hidden therein so that an external bulky andless attractively appearing line of pipe is made superfluous.

The rotary machine according to the invention for operation with amedium in at least two stages for compression or expansion of the sameby means of helical male and female rotors intermeshing with each otheris in first hand characterized in that respective pair of successivestages are connected by means of a channel or duct enclosed and builtinto the casing encircling the rotors.

A preferred solution in practice of the problem of the invention ischaracterized by an intermediate wall separating the pair of successivestages and provided with an internal hollow chamber having a firstopening in connection with the one pressure stage and the second openingin connection with the other pressure stage, of which the one openingacts as outlet from the one pressure stage and the other as inlet forthe other pressure stage.

The hollow chamber of the intermediate wall extends preferablyperpendicularly toa plane through the central axes of the rotors withthe inlet and outlet to the hollow chamber located diagonally inrelation to each other.

In such a design are further the inlet and outlet in respective pressurestage located diagonally in relation to each other.

Preferably the rotary machine according to the invenatent O tion is sodesigned that the high pressure ends of both pressure stages are locatedadjacent.

Other details and advantages characteristic of the invention will appearfrom the following description of an embodiment of the invention shownin the annexed drawlugs.

FIG. 1 shows a perspective view partly in section of a rotary machineaccording to the invention.

FIG. 2 shows a vertical longitudinal section of the rotary machine takenalong the line 2-2 in FIG. 3.

FIG. 3 shows a horizontal longitudinal section taken in the direction ofthe arrows 3-3 in FIG. 2.

FIG. 4 shows a horizontal longitudinal section taken in the direction ofthe arrows 4-4 in FIG. 2.

FIG. 5 shows a vertical cross-section along the line 55 in FIG. 2.

FIG. 6 shows a vertical cross-section along the line 66 in FIG. 2.

FIG. 7 shows a vertical cross-section along the line '7-7 in FIG. 4.

The rotary machine which is now to be described is constructed accordingto the principles given in the US. Patent 2,622,787 as regards thedesign of the helical profiles of the rotors and as regards theassemblage into two pressure stages according to the US. Patent2,804,260. The choice of these designs in combination with each other isto be regarded only as an example of a preferred embodiment, for whichreason the invention is not to be regarded as limited thereto but asembracing all the forms which are within the scope of the appendedclaims. As evident from FIG. 1 particularly, the rotary machineaccording to the invention is designed as a two-stage machine, morespecifically a compressor. In the casing, bores 10 and 12 are providedfor two rotor sets of which for the sake of clarity only the femalerotor set 14 is shown. By means of an intermediate wall 16 the casing isdivided into two stages, the one stage 18 containing the rotor sections20 of the low pressure stage and the other stage 22 the rotor sections24 of the high pressure stage. The rotor sections of the respectiverotor sets are interconnected in some suitable way at least in one ofthe rotor sets. As shown, the pitch of the rotor sections of the lowpressure stage is larger than the pitch of the rotor sections of thehigh pressure stage. The exemplified embodiment further shows that thewrap angle of the helical profile in the respective stages is mainly thesame, in the example approximately 240. The number of helical lands ofthe female rotor is six in the exemplified embodiment, implying that theset of female rotors cooperates with a set of male rotors provided withfour lands. Further the pitches of the rotor sections in the respectivestages are directed oppositely to each other in order to balance theaxial thrusts in both of the bearings which support each rotor set inend walls covering the ends of the housing. Since this design already isknown per se, these end walls have been omitted in the drawing in orderto make the same clearer.

In the low pressure stage 18 the casing is provided at the top with aninlet opening 26 for the working medium and at the bottom in the highpressure stage 2.2 with an outlet 28 for the fully compressed medium.

The intermediate wall 16, which divides the machine into the twopressure stages 18 and 22, is provided with bores 36) and 32. for amember which connects the rotor sections in each rotor set. These boresare preferably provided with an axial bearing 34 which may be dividedinto halves. Said axial bearing supports each rotor set in theintermediate wall and acts for that reason to prevent the deflectionwhich otherwise should occur if each rotor set was supported solely atits outer ends. If the length of the machine is shorter suchintermediate hearing, however, may be dispensed with and replaced by aconvenient sealing arrangement in order to reduce the dew losses throughthe intermediate wall.

As is evident from the drawings the intermediate wall 16 is hollow andthe hollow chamber 36 thus obtained acts as a connection between thehigh pressure stage 18 and the low pressure stage 22. The wall section38 facing the high pressure end of the low pressure stage 13 forms atthe bottom an outlet opening 40 for the working medium compressed in thefirst stage which via the hollow chamber 36 of the intermediate wall isconducted up to the upper part 42 of the portion of the casing whichencloses the high pressure stage 22. The hollow space 44 in said upperhigh pressure part 42 of the casing passes over into an inlet opening 46to the high pressure stage located at one outer end of the rotarymachine. The finally compressed working medium escapes through theoutlet 28 of the rotary machine which in its turn is located adjacentthe wall portion 48 of the intermediate wall which faces the highpressure end of the high pressure stage.

The inlet opening 26 is as evident from FIG. passing over into anextension 5% of the jacket portion 52 of the casing which closelyencircles the rotor parts; of the low pressure stage 18 for the rest.The object of this extension is to provide most favourable admission tothe workin g chamber of the low pressure stage.

The mainly vertical hollow chamber 36 in the intermediate wall 16separating the both pressure stages passes over as stated in the hollowspace 4 extending axially and enclosing the high pressure stagematerially as is evident from FIG. 6 according to which this hollowspace 44 extends around the rotors down to the high pressure outlet 28.In other words it may be said that the jacket portion 54 of the casingenclosing the high pressure stage is double walled and consists of anexternal supporting envelope 56 integral with the shell 52 of the lowpressure stage and a shell 58 closely encircling the rotor parts of thehigh pressure stage 22, between which shells 56 and 58 the hollow space44 is formed.

The double walled jacket portions 56 and 58 of the high pressure stagecontinues behind the intermediate wall 16 a short distance into theadjacent side of the low pressure stage as is evident from FIGS. 3, 4and 7 for the purpose of creating a smooth transition between the jacketportions enclosing the different stages. Since each rotor set has rotorsections in the different stages which are of the same rotor diameterthe jacket portions 52 and 58 are of the same diameter over the majorportions of their circumferences.

The illustrated casing is made in one piece but alternatively the casingmay be imagined as composed of an upper and a lower half, that is to saythe casing may be divided along a plane through the central axes throughthe rotors. A varied solution consists of joining the easing in axialdirection from suitable structural parts.

The rotary machine may as previously known operate dry that is to saythe rotors and the enclosing casing provide close clearances. Asalternative FIGS. 2 and 5 show a design provided with admission meansfor sealing and/ or cooling fluid such as oil or water to the low,pressure stage. An admission channel 60 distributes the fluid via anumber of channels 62 to the low pressure stage. In the deviceillustrated the fluid injection is efiected along the intersectionbetween both the bores and 12 but the location as well as the directionof inflow of the admission channels can be modified. Alternatively oradditionally the high pressure stage can be provided with such a fluidsupply.

We claim:

1. A two-stage rotary compressor of the helical screw type having acasing structure comprising a barrel portion providing two aligned setsof barrels for low and high pressure compression stages arranged intandem and in intersecting relation about coplanar axes, each of saidsets of barrels providing an inlet port located generally on one and thesame side of the plane of said axes and a discharge port locatedgenerally on the other side of said plane, said discharge ports beinglocated at the adjacent ends of the respective stages and the inletports being located at the ends of the respective stages remote fromeach other and said casing structure further providing two axiallyspaced apart partitions normal to said axes located between said sets ofbarrels to form end walls for the respective stages and a transverselyextending transfer passage therebetween, means providing separateconnecting passages each coaxial with one of said axes and extendingthrough said transfer passage to join said sets of barrels, an outercasing wall radially spaced from the barrels of the high pressure stageto provide an axially extending duct embracing the major portion of theperimeter of the high pressure stage, one end of said duct being in openand unrestricted communication with said transfer passage laterally toone side of the plane of said axes and the other end of said ductterminating in an opening providing said inlet port for said highpressure stage at the end thereof remote from the low pressure stage,said discharge port for the low pressure stage communicating with saidtransverse transfer passage laterally to the side of the aforesaid planeopposite said axially extending duct, and male and female rotor memberseach comprising axially spaced rotor sections having helical lands andgrooves disposed in intermeshing sets in said barrels and shaft portionsextending through said connecting passages to connect said sections.

2. A compressor as defined in claim 1 in which orifices are provided inthe barrel portion of the casing structure for injection of liquid intothe low pressure stage of the compressor. 7

3. A compressor as defined in claim 2 in which said orifices aredisposed substantially along the line of intersection between thebarrels 0n the same side of the plane of said axes as the discharge portfrom the low pressure stage.

References Cited in the file of this patent UNITED STATES PATENTS1,218,300 Nelson Mar. 6, 1917 1,531,607 Green Mar. 31, 1925 1,561,364Smith Nov. 10, 1925 1,626,768 Vollmann May 3, 1927 2,009,137 KlecknerJuly 23, 1935 2,804,260 Nilsson et a1 Aug. 27, 1957 2,808,007 GaubatzOct. 1, 1957 FOREIGN PATENTS 10,413 Australia of 1927 1,175,287 FranceNov. 10', 1958 1,249,171 France Nov. 14, 1960

1. A TWO-STAGE ROTARY COMPRESSOR OF THE HELICAL SCREW TYPE HAVING ACASING STRUCTURE COMPRISING A BARREL PORTION PROVIDING TWO ALIGNED SETSOF BARRELS FOR LOW AND HIGH PRESSURE COMPRESSION STAGES ARRANGED INTANDEM AND IN INTERSECTING RELATION ABOUT COPLANAR AXES, EACH OF SAIDSETS OF BARRELS PROVIDING AN INLET PORT LOCATED GENERALLY ON ONE AND THESAME SIDE OF THE PLANE OF SAID AXES AND A DISCHARGE PORT LOCATEDGENERALLY ON THE OTHER SIDE OF SAID PLANE, SAID DISCHARGE PORTS BEINGLOCATED AT THE ADJACENT ENDS OF THE RESPECTIVE STAGES AND THE INLETPORTS BEING LOCATED AT THE ENDS OF THE RESPECTIVE STGES REMOTE FROM EACHOTHER AND SAID CASING STRUCTURE FURTHER PROVIDING TWO AXIALLY SPACEDAPART PARTITIONS NORMAL TO SAID AXES LOCATED BETWEEN SAID SETS OFBARRELS TO FORM END WALLS FOR THE RESPECTIVE STAGES AND A TRANSVERSELYEXTENDING TRANSFER PASSAGE THEREBETWEEN, MEANS PROVIDING SEPARATECONNECTING PASSAGES EACH COAXIAL WITH ONE OF SAID AXES AND EXTENDINGTHROUGH SAID TRANSFER PASSAGE TO JOIN SAID SETS OF BARRELS, AN OUTERCASING WALL RADIALLY SPACED FROM THE BARRELS OF THE HIGH PRESSURE STAGETO PROVIDE AN AXIALLY EXTENDING DUCT EMBRACING THE MAJOR PORTION OF THEPERIMETER OF THE HIGH PRESSURE STAGE, ONE END OF SAID DUCT BEING IN OPENAND UNRESTRICTED COMMUNICATION WITH SAID TRANSFER PASSAGE LATERALLY TOONE SIDE OF THE PLANE OF SAID AXES AND THE OTHER END OF SAID DUCTTERMINATING IN AN OPENING PROVIDING SAID INLET PORT FOR SAID HIGHPRESSURE STAGE AT THE END THEREOF REMOTE FROM THE LOW PRESSURE STAGE,SAID DISCHARGE PORT FOR THE LOW PRESSURE STAGE COMMUNICATING WITH SAIDTRANSVERSE TRANSFER PASSAGE LATERALLY TO THE SIDE OF THE AFORESAID PLANEOPPOSITE SAID AXIALLY EXTENDING DUCT, AND MALE AND FEMALE ROTOR MEMBERSEACH COMPRISING AXIALLY SPACED ROTOR SECTIONS HAVING HELICAL LANDS ANDGROOVES DISPOSED IN INTERMESHING SETS IN SAID BARRELS AND SHAFT PORTIONSEXTENDING THROUGH SAID CONNECTING PASSAGES TO CONNECT SAID SECTIONS.